Thermomotive device



April 19, 1932. A. H. SANBORN THERMOMOTIVE DEVICE Filed Aug. 17, 1929 2 Sheets-Sheet 1' April 19, 1932.

A.- H. 'SANBORN 1,854,809

THERMOMOTIVE DEVICE Filed'Aug; 17, 1929 2 Sheets-Sheet 2 Eda/207" wt ZLW E 5042 5077a Patented Apr. 19, 1932 UNITED STATES PATENT" OFFICE COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS THERMOMOTIVE DEVICE Application filed August 17, 1929. Serial No. 386,537.

My invention relates to heat responsive de vices and, generally speaking, resides in the employment of a unitary member having two portions which are flexible in response to changes in temperature, there being provision for retarding the effect of temperature changes'upon one of said member portions with respect to such effect upon the other member portion. In the preferred embodiment of the invention this unitary member is inclusive of invar metal having substantially no coefiicient of expansion and'brass coupled therewith, the brass portion being constrained by the invar portion to flex in response to temperature changes. In the preferred embodiment of the invention the member upon which the temperature efiect is retarded is provided with a hood for this maintain a suitable circuit"'closed,

= When the device is subject to 9' member will be tion is employed for member portions are purpose. This hood confines a body of air in which this member portion is received and serves to retard the effect of temperature changes upon this member portion with respect to such eflfect upon the other member portion.

The device of my invention finds an important use in conjunction with switches which are to be operable in the presence of suddenly efiected excessive temperature, such as=is occasioned by sudden, accidental fires, for example. When the device of the inventhis purpose the two desirably coiled and in Similar directions, two similar ends of these portions being in substantially fixed relation and the other end "of one of these member portions being movable and the other end of the other member portion movable end engages a contact to normally such as a circuit containing a relay that governs a normally open alarm circuit, The device is desirably so adjusted that both the hooded and unhooded portions thereof will be similarly and sufliciently simultaneously afiected upon rise in temperature of 1 Fahrenheit or less per minute as not to disturb the circuits. rise in temperature of more than 1 Fahrenheit per minute, the hooded and unhooded portions of the sufliciently dissimilarly afbeing fixed. The P the retarding hood; F1g. 6 1s a vlew similar fected to occasion the alarm. If there is a sudden fire in the region of the device the unhooded portion, that may be also a switch contact, will separate from the contact complemental thereto since the hood about the other portion of the flexible member will prevent the sudden rise in temperature from quickly affecting it, so that the flexible member is, in effect, subject only to the sudden rise in temperature at the portion thereof that controls the switch when the sudden temperature rise is first initiated. Ultimately the hooded portion will be similarly affected to again bring the switch contacts into engagement, but the local alarm circuit will remain closed since the circuit of the relay that controls it was also opened at the relay armature when the relay circuit was first opened. The temperature range in which the device is to operate may be varied, if desired, by suitable adjusting means.

The invention will be more fully explained in connection with the accompanyin drawings in which-Fig. 1 diagrammatically indicates one embodiment-thereof minus the retarding hood, the circuit that may be employed in conjunction therewith, being also indicated; Fig. 2 is a view similar to Fig. 1 but indicating the hood in place and illustratin the eifect thereof, the circuit diagram eing omitted except for the contacts thereof; Fig. 3 is a diagrammatic illustration of another embodiment of the invention minus the retarding hood;Fig. 4 is a view similar to Fig.3 with the retarding hood present; Fig. 5 is a diagrammatic view of the referred embodimentof the invention minus to Fig. 5 with the retarding hood present; Fig. 7 is a sectional view illustrating the preferred mechanical construction'of the invention diagrammatically illustrated in Fig. 6, this figure being taken. on line 77 of Fig. 8; Fig. 8 is a sectional view on line 8-8 of Fig. 7; Fig. 9 is a sectional view on line 9-9 of Fig. 8; Fig. 10 is a sectional view on line 1010 of Fig. 7; andFig. 11 is a diagrammatic illustration showing one em ployment of the structure shown in Figs. 5 to 10 inclusive.

In the construction shown in Fig. 1 the strips of invar metal 1 and 2 are assembled with a strip 3 of brass, the invar strips being upon opposite faces of the brass strip. One invar strip is intimately joined with and throughout one half of the brass strip and the other intimately joined with and throughout the other half of the brass strip. One end of the flexible member comprised of the invar and brass strips is provided with a fixed anchorage 4. The other end of this member is movable to have engagement with a switch contact 5 constituting one terminal of a normally closed circuit, the flexible member constituting the other terminal of this circuit. This normally closed circuit includes a relay 6, a battery 7 and an armature of the relay, together with a normal contact 8 of this armature. Upon separation of the flexible member from the contact 5, the.

local circuit containing the relay 6 is opened, whereupon the retractile spring 9 moves the armature of the relay from its normal contact into engagement with the alternate contact of this armature, whereby a local alarm circuit is closed. The alarm circuit illustrated includes a signal bell 10 and an incandescent lamp 11. After the local circuit has been once opened it cannot be reclosed by the mere engagement of the contact 5 by the flexible member complemental thereto since there would then be another gap in the circuit at the contact 8. The flexible member is provided with knife edge mountings illustrated at 12 and 13. Fig. 1 indicates the flexible member 1, 2, 3, 4 with all of its parts equally subject to temperature changes. The

dotted lines in this figure indicate a flexure of the flexible member, due to temperature rise, which will not remove this flexible member from engagement with the contact 5 since the flexing in each portion of the flexible member counteracts the flexing of the other in so far as changing the contacting relation of said member with this contact 5 is concerned. The structure of Fig. 1 is completed, in accordance with the preferred emodimentpf my invention, by the addition of a hood 14 which surrounds the flexible member portion that is inclusive of the invar strip 2 and the half of the brass strip 3 that is coupled therewith. This hoodconfines a body of air in which the contiguous member portion is received and serves to retard the effect of temperature changes upon this member portion with respect to such effect upon the other member portion. The hood may have a heattinsulating lining 14. If the temperature rise is slow, such as 1 Fahrenheit or less per minute, the hood will permit the flexible member to flex, as indicated in Fig. 1, in which event the relay circuit will remain closed. If the temperature change is more than 1 Fahrenheit per minute, the hood will retard the effect of the temperastrips 3, 3 which are respectively faced by the invar strips 1 and 2. The two pairs of unlike strips are coupled b a shaft 15 which may be pivotally mounte at its ends, this shaft thus serving to incorporate the four metal strips into a unitary member. The flexible portion 1, 3 of the flexible member may be in fixed relation with the shaft as by means of a set screw 16. The flexible portion 2, 3 may have a fixed anchorage 4',

at one end, and may pass through a slot in the shaft 15, at its other end, there tahave sliding relation with said shaft. Fig. 3 illustrates how the two portions of the flexible member will flex alike, when subject to similar temperature rises, the contact 5 consequently remaining in constant engagement with the member portion 1, 3. When, however, the member portion 2, 3 has the hood 14 applied thereto, as indicated in Fig. 4, this member portion will not initially respond to the selected sudden rise in temperature, the member portion 1, 3' then having opportunity to flex away from the contact 5 to open the relay circuit, with the results described.

The structures of Figs. 5 and 6 are generally similar to the structures of Figs. 3 and 4 and have the same operation with the exception that the heat responsive. strips are coiled around the shaft in similar directions. The

relay circuit will, with the apparatus illustrated, remain closed during temperature changes that are, in the example chosen, 1 Fahrenheit or less per minute, but when the temperature change is a rising temperature and is more than 1 Fahrenheit then the relay circuit will be opened, with the results stated.

Referring more particularly to Figs. 5 and 6, and also to the subsequent figures, one flexible member portion is inclusive of a brass strip 17 and an invar strip 18 which are together coiled about the shaft 15. One end of this member portion is fixed to this shaft and the other end of this portion is in separable engagement with the contact 5, this member portion itself, also constituting a contact complemental to-the contact 5. The other flexible member portion is inclusive of a brass strip 19 and an invar strip 2Q which are coiled and assembled with the shaft 15 similarly to the member portion 17, 18. Both coiled portions of the flexible member are coiled in similar directions and have two similar ends fixedly connected by the shaft 15 since, due

45 claim to the coiling, it is unnecessary to provide the slipping relation which is present between the member 2, 3 and the shaft of the structure shown in Figs. 3 and 4. The 5 outer end of the member portion 19, is provided with a fixed anchorage, as indicated at 21. For reasons which have been hitherto fully set. forth, there will be no change in the relation of the contact 5 and the contact 17, '18 due totemperature rise, whether this rise is sudden or slow, if no provision is made for retarding the efiect of temperature changes upon one of the members, as indicated in Fig. 5. If, however, the hood 14 is added, as indicated in Fig. 6, the contact 17, 18 will separate from the contact 5 upon rise in temperature if this rise is sufficiently rapid. The contact 5 may be in the form of a screw which is threaded into a bracket 5'. When the con- 20 tact 5 is thus arranged, the extent of temperature rise, which is required to efiect separation of the contact in the relay circuit, may

be varied.

Where the implement is employed for the is specific purpose stated, it is desirably mounted upon an insulating block 22. The shaft 15 may be journaled in the sides of a U- shaped bracket 23 which is secured to block 22. The entire structure may be covered by another hood 24 to guard the structure, this hood being provided with large so as to have no retarding efiect of the temperature changes upon the structure, the hood 14 on the other hand, being preferably imperforate so as to have such retarding efi'ect with relation to the flexible member portion enclosed thereby.

The switchingmechanism herein disclosed forms the subject matter of my copending ap- 40 plication Serial No. 472,017, filed July 31,

Changes may be made without departing from the invention.

Having thus described my invention, it

1. A heat responsive device inclusive of a unitary member having two portions coiled in similar directions with two similar ends of said portions in substantially fixed relation and the other end of one of said member portions movable and the other end of the other of said member portions fixed, said coiled member portions being expansible and contractible in response to temperature changes, there being provision for retarding the effect of temperature changes upon one of said member portions with respect to such efiect'u on the other member portion.

2. A eat responsive device inclusiveof a unitary member having two portions coiled in similar directions with two similar ends of. said portions in substantially fixed relation and the other end of one of said member portions movable and the other end of the other of said member portions fixed, said perforations,

coiled member portions being expansible and contractible in response to tem erature changes, in combination with a hoo for one of said member portions which confines a body of air in which this member portion is received and serves to retard the effect of temperature changes upon this member portion with respect to such efiect upon the other member portion.

3. A heat responsive device inclusive of a unitary member having two portions which are flexible in response to changes in temperature, said member having a normally permanent position with respect to a fixed contact, and means for retarding the effect of temperature changes upon one of said member portions with respect to such effect upon the other member portion whereby the member alters its position with respect to the fixed contact.

d. A heat responsive unitary member having two portions which are flexible in response to changes in temperature, said member normally engaging a fixed contact throughout said temperature changes, there being provision for retarding the efiect of temperature changes upon one of said member portions with respect to such efiect upon the other member portion whereby the fixed contact is disengaged.

5. A heat responsive device inclusive of a unitary member having two portions coiled in similar directions with two similar ends of said portions in substantially fixed relation, said coiled member portions being expans'ble and contractible in response to temperature changes, said member having a normally permanent position with respect to a fixed contact, and meansfor retarding the efiect of temperature changes upon one of said member portions with respect to such efiect upon the other member portion whereby the member alters its position with respect to the fixed contact.

6. A heat responsive device inclusive of a unitary member having a free end and a fixed end; a fixed contact engageable with said free end; means for flexing said memher in response to changes in temperature, said "free end normally engaging the contact throughout said temperature changes; and means for retarding the effect of temperature changes upon one portion of said flexible member whereby the free end of the member is disengaged from the fixed contact.

7 A heat responsive device inclusive of a unitary member having a free end and a fixed end;,a fixed contact engageable with said free end; means for flexing said member in response to changes in temperature, said tree end normally engaging the contact throughout said temperature changes; and a heat insulating hood for retarding the effeet of temperature changes upon one pordevice inclusive of a tion of said flexible member whereby the free end of the member is disengaged from the fixed contact.

8. A heat responsive device inclusive of a unitary flexible metal member having strips of metal of a different coefficient of ex an.- sion from said member upon opposite Ewes thereof, one said strip being intimately joined with and throughout one half of the member and the other intimately joined with and throughout the other half of the member,

said member being fixed at one end and free at the other end; a fixed contact engageable by said free end; knife-edge mountings midway of said member; and a heat insulating hood enclosing the portion of said member between said mounting and its fixed end.

I 9. A heat responsive device inclusive of a member having two flexible portions respectively faced by strips of metal of a different coeflicient of expansion from said member; a shaft coupling said portions, one said portion being in fixed 'relation with the shaft at one end ofsaidportion and in movable relation with a fixed contact at its other end,

the other portion having a fixed anchorage at one of its ends and at its other end passing through a slot in the shaft; and a heat insulating hood enclosing said latter portion.

10. A heat responsive device inclusive of a unitary member having two flexible coiled portions respectively faced by strips of metal of a different coeflicient of expansion from said members, a shaft fixedly connectin the inner ends of the coils, the outer end 0 one of the coils being free and engageable with a fixed contact, and the outer end of the other coil having fixed anchorage; and a heat insulating hood enclosing one of the coils.

In witness whereof, I hereunto subscribe my name.

, ARTHUR H. SANBORN. 

